Excretion questions

HideShow resource information
  • Created by: Steff06
  • Created on: 01-03-16 19:18
Define excretion
The removal of metabolic waste from the body.
1 of 16
Which 2 products are produced in large amounts and have to be excreted?
Carbon dioxide produced in respiration and nitrogen-containing compounds such as urea.
2 of 16
How is carbon dioxide removed from the body?
Passed into the blood and transported to the lungs. Here it diffuses into the alveoli to be excreted as we breathe out.
3 of 16
How is urea produced?
By breaking down excess amino acids (deamination).
4 of 16
How is urea excreted?
Urea passed into bloodstream and transported to the kidneys. Removed in kidneys to become part of urine.
5 of 16
Why does carbon dioxide have to excreted?
Excess CO2 is toxic. High levels of CO2 has 3 main effects.
6 of 16
What is the 1st effect of high levels of CO2?
CO2 is carried in blood as hydrogencarbonate ions. Hydrogen ions also formed under influence of enzyme carbonic anhydrase. Hydrogen ions combine with haemoglobin. Too much CO2 reduces oxygen transport.
7 of 16
2nd effect of high levels of CO2
CO2 combines directly with haemoglobin to form carbaminohaemoglobin which has a lower affinity for oxygen than haemoglobin.
8 of 16
What is the 3rd effect of high levels of CO2?
Excess CO2 can cause respiratory acidosis where CO2 dissolves in blood plasma. Here it combines with water to produce carbonic acid.
9 of 16
What does the carbonic acid then do?
Dissociates to release hydrogen ions which lower the pH, making the blood more acidic.
10 of 16
What do proteins in the blood do?
Act as a buffer to resist the change in pH.
11 of 16
What effect does a small change in the pH have?
Causes excess hydrogens to be detected by respiratory centres in medulla oblongata. Increase in breathing rate to remove excess CO2.
12 of 16
What does a large change in the pH cause?
Respiratory acidosis. Symptoms include headaches, drowsiness, tremors, confusion.
13 of 16
Why must nitrogenous compounds such as urea be removed?
Body cannot store proteins/amino acids. Amino acids transported to liver and toxic amino group removed by deamination.
14 of 16
What does the amino group initially form?
The highly soluble and highly toxic ammonia.
15 of 16
What is ammonia converted to?
The less soluble and less toxic compound urea. Urea transported to kidneys for excretion.
16 of 16

Other cards in this set

Card 2

Front

Which 2 products are produced in large amounts and have to be excreted?

Back

Carbon dioxide produced in respiration and nitrogen-containing compounds such as urea.

Card 3

Front

How is carbon dioxide removed from the body?

Back

Preview of the front of card 3

Card 4

Front

How is urea produced?

Back

Preview of the front of card 4

Card 5

Front

How is urea excreted?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Cellular processes resources »